[m_0x]

> if you select a timestamp value Postgres can convert it from UTC to the timezone you want

I dread timestamp issues. Hard to understand what happens and how to fix them.

You mention "if necessary". How does postgres knows if a conversion is necessary?

[paulryanrogers]

If the value has a TZ offset it'll know. If it doesn't but the session TZ differs from UTC then it'll know. With non-TZ timestamp both cases could store the wrong timestamp and it might be impossible to catch or correct without the original data or more context.